An airbag system is an example of a supplemental restraint system for an automobile and has been developed to protect vehicle occupants from sustaining injuries during automotive crashes. During an automotive crash, an airbag is rapidly filled with inflation gas to provide an energy-absorbing cushion between the vehicle occupant and a hard surface of the vehicle. The inflated airbag absorbs the vehicle occupant's energy to provide a gradual, controlled deceleration of the vehicle occupant, and the airbag also provides a cushion for distributing the loads on the vehicle occupant. Airbags are placed in a number of different locations in the automobile. Airbags installed in the doorframe or in the seat of the automobile are known as side airbags. The side airbags protect vehicle occupants during side impact crashes and rollovers; the side airbags protect vehicle occupants from colliding with doors, pillars, and/or the roof of the automobile.
An inflator is the device in the airbag system that releases inflation gas into the folded airbag. The inflation gas rapidly fills the airbag in a fraction of a second so the airbag is fully deployed before the vehicle occupant interacts with the airbag. A common type of inflator suitable for inflating a side airbag is a pyrotechnic inflator. A pyrotechnic inflator contains pyrotechnic material or gas generant. The gas generant is an exothermic chemical mixture, and upon ignition, the gas generant produces gaseous combustion products or inflation gas. The inflation gas exits the inflator and flows into the folded airbag.
The pyrotechnic side impact inflator needs to be of a relatively small size to meet the stringent size and configuration limitations for side impact inflators. Co-assigned United States patent, U.S. Pat. No. 6,065,774, teaches a tubular side impact inflator having a filtration system consisting of a bed of expanded metal chips. U.S. Pat. No. 5,556,131 teaches a simple and small size pyrotechnic side impact inflator.
Since side airbags are being installed in increasing number of automobiles each year, there is a desire to develop simpler and cheaper pyrotechnic side impact inflators.